<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <meta http-equiv="X-UA-Compatible" content="ie=edge">
    <title>Document</title>
</head>
<body>
    <script>
        /* 
        pop()  //从后面删除
        shift()   //从前面删除
        splice(index,howmany)  //index:从哪一个下标开始  howmany：删除多少个
         */
        var arr=[1,2,3,4]
        arr.pop();
        arr.shift()
        console.log(arr) 
          
        var app=[1,2,3,4,5,6]
        console.log(arr) 
        app.splice(2,3)
        console.log(app)   //1 2 6
    </script>
</body>
</html>